Peanut Skin Polyphenols Prove Effective in Lowering Lipid Levels

Peanut Skin Polyphenols Prove Effective in Lowering Lipid Levels

November 03, 2013

Rishipal Bansode, PhD, with the North Carolina Agricultural and Technical State University’s Center for Excellence in Post-Harvest Technologiesat the NC Research Campus, recent findings published in the journal Food Chemistry demonstrated in an animal model that peanut skin polyphenols, specifically A-type procyanidin, can lower lipid levels. The findings are part of the process to develop a heart-healthy ingredient made from the peanut skin extract that can be added to other foods to enhance their nutritional value.

When many people see peanut skins, they think of the garbage can. Scientist Rishipal Bansode, PhD, thinks of the plethora of health-promoting polyphenols the reddish, paper-thin skins contain.

Bansode is investigating peanut skins as a potential food ingredient that can be used to enhance the nutritional value of other foods. Since the thought of munching on peanut skins is not too appetizing for most people, Bansode has reduced them to a powder from which he is able to extract the polyphenols.

Polyphenols are a class of phytonutrients in plants that are linked to numerous health benefits such as preventing cardiovascular disease, some types of cancers, neurodegenerative disorders, osteoporosis and diabetes. An analysis of Bansode’s peanut-skin extract conducted by the David H. Murdock Research Institute (DHMRI) revealed over 20 polyphenols. The DHMRI is a contract research organization providing analytical and advanced technologies located on the NC Research Campus.

“The important thing we are looking at is the procyanidins, specifically the A-type, which are condensed tannins and oligomers of catechin and epicatechin, and are unique to peanut skins,” Bansode said.

In the paper “Bioavailability of Polyphenols from Peanut Skin Extract Associated with Plasma Lipid Lowering Function” published in the journal Food Chemistry, Bansode and co-authors from NC A&T and Qatar University, proved the bioavailability of these peanut-skin procyanidins in an animal model. They looked specifically at their relationship to lowering blood lipids or the level of fats like cholesterol and triglycerides. When lipid blood levels are too high, the condition is called hyperlipidemia and can increase the risk of developing heart disease.

Bansode explained that within 30 to 60 minutes of receiving the peanut skin extract, the study animals experienced a spike of procyanidin A that demonstrated how “readily the extract gets absorbed in the blood and starts having biological effects.” Bansode and his fellow researchers also found that the animals, which were fed a high-fat diet, experienced a loss of body weight due to a reduction of epididymal or belly fat.

“We started seeing extremely significant reduction in saturated fats, monounsaturated fats and polyunsaturated fats. We didn’t expect the reduction in polyunsaturated fats. We expected an increase, but we found a decrease in all categories of fats,” he said. “So there are two things. One is the intestinal absorption of polyphenols that can inhibit the absorption of triglycerides into the body. Another is genetic regulation. We think that polyphenols can inhibit fatty acid synthesis and promote the transportation to parts of the body where it is metabolized.”

Bansode is conducting additional cell culture studies to understand the mechanism by which procyanidins in the peanut skin extract work to reduce lipid levels. His recent findings are a follow-up to previous research that also demonstrated that peanut skin extract lowers lipid levels in blood and potentially prevents hepatic steatosis (also known as fatty liver). Bansode’s research continues NC A&T’s history of peanut research including studies by Jianmei Yu, PhD, a food processing and food chemistry scientist in NCA&T’s Department of Family and Consumer Sciences.

Over two million metric tons of peanuts are raised in the United States annually, mostly in the Southeast. For Bansode and his colleagues that means a sizeable opportunity to turn an agricultural waste product that is primarily fed to animals into a health-promoting functional food ingredient for people.

As for peanut shells, they are not being left to the rubbish pile. NC A&T scientists are researching their use as a fertilizer and a purification method for municipal drinking water and wastewater.